Frozen thin-sections of newly forming bone, resorbing bone and other tissues involved in mineral translocation will be prepared and subjected to ultramicroincineration. Morphological and chemical evaluation of the mineral residue will be performed by energy dispersive x-ray analysis. Freeze-substitution techniques, which reveal more subcellular detail, will also be used for some of these tissues for comparison with the frozen thin-sections. BIBLIOGRAPHIC REFERENCES: Schraer, H. and Gay, C.V.: Electron microscope studies on frozen thin-sections of bone. Fifth International Congress of Histochemistry and Cytochemistry, Bucharest, Romania, 1976 (Abstract). Clermont, C. and Schraer, H.: Inhibition of erythropoiesis in Japanese quail by estrogen. Fed. Proc., 1977 (Abstract).